Method for packaging electronic devices and integrated circuits

ABSTRACT

The present invention relates to the field of electronic devices and their associated driver and/or controller integrated circuits and in particular to the mechanical packaging of electronic devices and to the packaging of electronic devices and their associated driver and/or controller integrated circuits.

FIELD OF THE INVENTION

The present invention is related to the field of electronic devices andtheir associated driver and/or controller integrated circuits, and moreparticularly to the mechanical packaging of electronic devices and tothe packaging of electronic devices and their associated driver and/orcontroller integrated circuits.

BACKGROUND OF THE INVENTION

Electronic devices respectively electronic components such asmicro-electromechanical system (MEMS) devices are of increasingimportance. Many type of systems use sensors to detect the value of aproperty of a physical system and to generate a corresponding electricalsignal representing the sensed value.

Accelerometer sensors for example comprise a mechanically activecomponent, e.g. an acceleration dependant oscillating mass and rely onelectromechanical sensors, which translate particular types ofacceleration, such as rotational or linear acceleration, intocorresponding electrical signals.

Since such electronic devices are quite sensitive, they need to beprotected by assembling them in some kind of package. For themanufacturing of electronic or other devices for micro systems manytechnologies have been developed, which enable precise forming ofstructured encapsulation or passivation layers and/or cavities.

Typical packaging or housing concepts, as for example moulding inplastics, are disadvantageous because the mechanical properties of saidsensitive components are disturbed or even damaged. In case ofSAW-filter-devices for instance even the material on the surfaceinfluences the characteristics of said filter devices.

To avoid such disturbance and to protect such sensitive electronicdevice, wafers with corresponding sensitive electronic devices arebonded with a second wafer or a lid wafer. Said second wafer comprisesholes or trenches in the area or at the position of said electronicdevices. These holes or trenches of said second wafer are fabricated insuch a way that they form a cavity above the sensitive structures afterbonding said second wafer to said first wafer.

DE 101 47 648 A1 for example discloses this concept for the fabricationof pocket-shaped structures for a glass lid used for packaging MEMSdevices.

Alternatively also expensive ceramic packages are used to protectsensitive components.

DE 102 06 919 A1 discloses a method for packaging electronic devicesusing a process with the following steps: Putting said electronicdevices on a first wafer, fabricating a frame structure around eachelectronic device and covering said frame structure with a lid structureplaced on a victim layer. The frame structure around each electronicdevice and the covering form a cavity housing and protecting theelectronic device. As already mentioned above, many types of systems useelectronic devices such as sensors to detect the value of a property ofa physical system and to generate a corresponding electrical signalrepresenting the sensed value. These electrical signals are commonlyprovided to electrical integrated circuits, located off-chip or inadjacent locations on-chip, in order to enable a desired function, e.g.amplification, discrimination and/or signal conversion, to be performed.

In the case of a separate packaging of electronic device and associateddriver and/or controller integrated circuit, the packaged electronicdevice is mounted on a printed circuit board along with the driverand/or controller integrated circuit, which is packaged in a similarmanner. Collectively they perform the desired function, e.g. a sensingfunction.

Since the packaging of the electronic device and the packaging of theintegrated circuit are generally significantly larger than thecorresponding electronic device respectively the integrated circuit, thepackaging contributes notably to the dimensions and also to the costs ofthe assembly on the printed circuit board.

Further, the mounting of the electronic device in the packaging limits,how close the electronic device can be placed with respect to theintegrated circuit performing the controller and/or driver function.This can in turn unnecessarily limit the electrical performance of theelectronic system or increase the susceptibility to noise.

WO 01/29529 A2 discloses a packaging of micro-mechanical sensors andassociated control circuits. The micro-mechanical sensor is fabricatedon a semiconductor wafer and the control circuit on a anothersemiconductor. A cavity is etched on the back side of the controlcircuit wafer, the cavity being formed such that the sensor on the otherwafer fits within the cavity when the wafers are brought together in anadjoining relation.

Therefore, it is the object of the present invention to provide an easy,size and cost reduced but safe concept to package or house electronicdevices or electronic devices together with their associated driverand/or controller integrated circuits, in particular by usingconventional integrated circuit fabrication techniques and conventionalpackaging technologies.

GENERAL DESCRIPTION OF THE INVENTION

The inventive solution of the object of the present invention issurprisingly achieved by each of the subject matter of the respectiveattached independent claims. Advantageous and/or preferred embodimentsor refinements are the subject matter of the respective attacheddependent claims.

Accordingly, the invention proposes a method for packaging electroniccomponents comprising the steps of providing at least one supportsubstrate; producing at least one recess in a top side of said supportsubstrate comprising at least one stair, placing at least one firstelectronic device at least partially onto said stair, in particular tosupport said first electronic device and/or to space said firstelectronic device from a bottom of said recess and covering at leastpartially said top side of said support substrate with a lid.

The step of covering said top side of said support substrate with a lidresults in the formation of a cavity being constituted by said recessand said lid. Accordingly, said first electronic device is housed in orwithin said cavity. In one embodiment beside the first electronic deviceat least one second electronic device is placed on said top side of saidsupport substrate. Preferably said second electronic device is placedadjacently to said recess.

The invention further proposes a method for packaging electroniccomponents comprising the steps of providing at least one supportsubstrate, producing at least one recess in a top side of said supportsubstrate, placing at least one first electronic device into saidrecess, arranging, in particular adjacently to said recess, at least onesecond electronic device on or onto said top side top side of saidsupport substrate and covering at least partially said top side of saidsupport substrate with a lid.

Hereby, the step of covering said top side of said support substratewith a lid or a cover also results in the formation of a cavity built upby said recess and said lid. Accordingly, said first electronic deviceis housed in or within said recess and said second electronic device isencapsulated simultaneously. The housing of said first electronic deviceand the encapsulation of said second device are performed in only onestep. In one alternative of this embodiment said recess is alsomanufactured with at least one stair to support said first electronicdevice and to space said first electronic device from a bottom of saidrecess.

The present invention also proposes an electronic package comprising atleast one support substrate having at least one recess in a top sidewherein said recess comprises at least one stair, at least one firstelectronic device arranged at least partially onto said stair spacingsaid first electronic device from the bottom of said recess and a lidcovering at least partially said top side of said support substrate.Above proposed electronic package is in particular producible orproduced with a method according to the present invention.

Said electronic package comprises a cavity which houses said firstelectronic device and which is formed by covering said recess with saidlid. In one embodiment the electronic package further comprises at leastone second electronic device being arranged, in particular adjacently tosaid recess, on said top side of said support substrate.

The invention further proposes an electronic package comprising at leastone support substrate having at least one recess in a top side, at leastone first electronic device arranged within said recess, at least onesecond electronic device arranged, in particular adjacently to saidrecess, on said top side of said support substrate and a lid covering atleast partially said top side of said support substrate. Above proposedelectronic package is in particular producible or produced with a methodaccording to the present invention.

Accordingly, said electronic package comprises both a cavity whichhouses said first electronic device and an encapsulation of said secondelectronic device, both formed by covering said support substrate withsaid lid. In a preferred embodiment said recess comprises at least onestair onto which said first electronic device is at least partiallyarranged and which spaces said first electronic device from the bottomof said recess.

Several embodiments of the electronic package are explicitly mentioned.However, since said electronic package is particularly producible orproduced by the inventive method, the features of the above and belowdescribed method according to the invention correspond also to means orcomponents of the electronic package being produced by said methodfeatures.

Said first electronic device comprises MEMS devices such as SAW filterdevices, quartz device, thermo sensors, pressure sensors and/or orgyroscopes. In further embodiments said first electronic devicecomprises sensorial function elements, semiconductor function elements,thermo function elements, mechanical function elements and/or opticalfunction elements. The first electronic device according to theinvention has a thickness or a height in the order of 1 .mu.m up to 1000.mu.m, preferably in the order of some tens .mu.m or 50 .mu.m up to somehundreds .mu.m or 200 .mu.m and a diameter in the order of 1 .mu.m up tosome tens mm, preferably in the order 10 .mu.m up to 10 mm.

Said support substrate can be provided as a semiconductor substrate. Inone embodiment a Silicon semiconductor is provided as said semiconductorsubstrate. In another embodiment a compound semiconductor comprising thematerials GaAs, InP and/or SiGe is provided as said semiconductorsubstrate.

Another embodiment uses a semiconductor being characterized by a wideenergy gap as said semiconductor. The energy gap is in the order of 2.5eV up to 10.0 eV, preferably in the order of 3.0 eV up to 6.0 eV. Inthis case a sapphire is a preferred semiconductor substrate.

The fabrication of said recess on said top side of said supportsubstrate is performed by a subtractive process such as etching, lappingand/or sand blasting. The dimensions of said recess are adapted to thedimensions of the first electronic device to accommodate. The dimensionsof the recess need to be chosen such that said first electronic devicedives, in particular in essential, completely into said recess.Accordingly, said recess has a depth in the order of 1 .mu.m up to 1000.mu.m, preferably in the order of 50 .mu.m up to 200 .mu.m and adiameter in the order of 1 .mu. 1 m up to some tens mm, preferably inthe order 10 .mu.m up to 10 mm.

Some embodiments comprise, as already described above, the feature of arecess provided with at least one stair to support and to space saidfirst electronic device from a bottom of said recess. The dimensions ofsaid stair are dependent on the size of the recess. Accordingly, thestair height is smaller than the recess depth and the stair length issmaller than the recess diameter. Said stair has a height in the orderof 1 .mu.m up to 400 .mu.m, preferably in the order of 50 .mu.m up to200 .mu.m and a length in the order of 1 .mu.m up to some tens mm,preferably in the order of 10 .mu.m up to 10 mm. The total stair heightor the average stair height corresponds to about 1% to 80%, preferably10% to 60% of the total recess height or the average recess height. In aparticular preferred embodiment said stair height corresponds to about20% to 50% of the total recess height or the average recess height. Thestair length corresponds to about 1% to 80%, preferably 3% to 40% of thetotal recess length or the average recess length. In a particularpreferred embodiment said stair length corresponds to about 5% to 30% ofthe total recess length or the average recess length.

Said first electronic device is mounted on said stair by gluing,soldering, low temperature glass molding and/or pasting, in particularAg pasting. Hereby, said first electronic device can be movable mounted.In a particular embodiment this kind of mounting enables the firstelectronic device to oscillate. The fabrication of said recess isperformed by varying the parameters of the above mentioned subtractiveprocess to fabricate the recess.

If the recess according to the invention comprises a stair, said staircan be produced in an one-step-process or in a multi-step-process. Forinstance, a one-step-process can be realized by a lapping tool or a kindof lapping stamp having the shape corresponding at least essentially tothe negative shape of the recess and stair. An example for amulti-step-process corresponds to the application of lapping tools ofdifferent sizes and/or shapes. The application combination of saiddifferent lapping tools enables the formation of recesses and thecorresponding stair. Another example for a multi-step-processcorresponds to an etching process using photo-lithographic structuring.

In one embodiment said second electronic device is provided as anintegrated circuit. Said integrated circuit can be provided or producedas a solid state or monolithic integrated circuit, as a film integratedcircuit and/or as a hybrid integrated circuit. In another embodimentsaid integrated circuit is provided as a driver or controller integratedcircuit for said first electronic device. In a further embodiment saidintegrated circuit comprises both function, i.e. being both driver andcontroller integrated circuit for said first electronic device.

To avoid or reduce electronic noise, for instance during a transmissionof an electrical signal from said first electronic device to said secondelectronic device or vice versa, said second electronic device is placedas close as possible to said first electronic device. For instance, saidsecond electronic device directly verges on the upper edge of saidrecess. Preferably said first electronic device and second electronicdevice are electrically connected. This connection is performed by wirebonding, soldering and/or metal pasting comprising the materials Au, Al,PbSn, SnAgCu and/or Ag.

The mounting or producing method as well as the dimensions of the secondelectronic device or integrated circuit are dependent on its embodiment.Said second electronic device is mounted on said top side by gluing,brazing, soldering, low temperature glass molding and/or pasting, inparticular Ag pasting, respectively is produced by evaporation, CVD,sputtering, epitaxial growth and/or dotation.

At least one first electrical contact pad is deposited on said top sideof said support substrate, in particular adjacent to said recesscontaining said first electron device. Said first electrical contact padis fabricated by photo-lithographic techniques using for instance PVD,in particular evaporation and/or sputtering, and/or CVD. The materialsforming said first electrical contact pad comprise Au, Al, TiCu, AlSiCu,AlSiTi, W, Cu and/or AlCu. Said first contact pad comprises a thicknessin the order of 1 nm up to some tens .mu.m, preferably in the order of100 nm up to 1 .mu.m and a diameter in the order of 1 .mu.m up to somehundreds .mu.m, preferably in the order of 10 .mu.m up to 500 .mu.m.Said first electrical contact pad is in particular electricallyconnected with said first electronic device. This connection isperformed by wire bonding, soldering and/or metal pasting comprising thematerials Au, Al, PbSn, SnAgCu and/or Ag.

According to the corresponding embodiments at least one secondelectrical contact pad is arranged on said top side of said supportsubstrate, in particular adjacently, to said second electron device tocontact said second electronic device. Said second electrical contactpad can be fabricated by using the same techniques and materials asmentioned above for said first electrical contact pad. Preferably thefirst and the second electrical contact pad are fabricatedsimultaneously in one step. Said second electrical contact pad iselectrically connected with said second electronic device. Thisconnection can be performed according to the above described connectionbetween said first electronic device and said first electrical contactpad.

Said support substrate is covered by said lid or cover in an adjoiningrelationship. This covering leads to the formation of a cavity by saidrecess housing the first electronic device. According another embodimentof the present invention having both said first electronic device insaid recess and second electronic device on said top side of saidsupport substrate, the covering of the support substrate by said lidforms both a cavity housing the first electronic device and anencapsulation for said second electronic device simultaneously. Theinventive method eliminates the need for a separate packaging ofelectronic devices and their corresponding integrated circuits. Thedisclosed packaging method advantageously eliminates the handling ofexposed sensors during packaging operations, and results in a closerplacement of the electronic device and its associated integratedcircuit, so that cost are reduced and greater systems performance can beachieved using common packaging technologies.

Preferable materials for said lid comprise glass, metal, ceramic,semiconductor and/or plastic and can be provided as a film. Dependent onits material said lid comprises a thickness in the order of 10 .mu.m upto some mm, preferably in the order of 100 .mu.m up to 1 mm. Said lidcovers at least partially said support substrate. In a furtherembodiment the diameter of said lid corresponds essentially to thediameter of said support substrate to cover.

A contact side of said lid touching at least partially said top side ofsaid support substrate is provided flat, i.e. non-structured, so thatsaid contact side of said lid is entirely in touch with said top side ofsaid support substrate. In another embodiment said contact side of saidlid, which touches said top side of said support substrate, is providedstructured, i.e. comprising a first recess in the area of said firstelectronic device. In this particular embodiment the cavity, whichhouses said first electronic device is formed by said recess in saidsupport substrate and by said recess in said lid. In another embodimentsaid contact side of said lid is provided structured such that saidcontact side comprises a first recess in the area of said firstelectronic device or a second recess in the area of said secondelectronic device. In a further embodiment said contact side of said lidis provided structured such that said contact side comprises a firstrecess in the area of said first electronic device and a second recessin the area of said second electronic device. Accordingly, said contactside of said lid is provided structured comprising at least one recessin said lid contact side. In this particular embodiment beside thecavity, which houses said first electronic device and which is formed bysaid first recess, also a cavity is formed by said second recess, whichhouses said second electronic device.

Said top side of said support substrate and said contact side ofcovering said lid are bonded together. Possible techniques for bondingsaid top side of said support substrate and said contact side of saidlid together are anodic bonding, low-temperature-bonding, brazing,gluing, soldering and/or glass melting, in particular low temperatureglass melting. According to one embodiment said contact side of said lidand/or said top side of said lid is respectively are covered at leastpartially with at least one adhesive layer and said support substrateand said lid are bonded together via said at least one adhesive layer.Said adhesive layer comprises a thickness in the order of 100 nm up tosome tens .mu.m, preferably in the order of 1 .mu.m up to 10 .mu.m and adiameter corresponding in particular essentially to the diameter of saidlid or said support substrate to cover. In another embodiment bothsides, i.e. said contact side of said lid and said top side of saidsupport substrate are covered with at least one adhesive layer and saidsupport substrate and said lid are bonded via said adhesive layers.Since it is easy to deposit, in a preferred embodiment the adhesivelayer covers entirely said contact side of said lid.

In another embodiment said adhesive layer comprises at least one gap orrecess. In one embodiment said adhesive layer comprises at least onefirst gap or one first recess in the area of said first electronicdevice or said recess and/or a second gap or second recess in the areaof said second electronic device. Accordingly, the corresponding recess,which accommodates said first electronic device, and/or said secondelectronic device is respectively are not covered by said adhesive layerenabling the possibility of using electronic devices sensitive to saidadhesive layer. Said adhesive layer is for instance realized by gluing,blazing, soldering and/or glass layer melting. Possible materials inaccordance to above mentioned methods forming said adhesive layer areresin, preferentially epoxy resin and/or acrylic resin, AuSn, PbSn,SnAgCu and/or low temperature melting glass. Said adhesive layer isdeposited by spin coating, spray coating, PVD, in particular sputteringand/or evaporation, screen printing and/or filming. In a preferredembodiment of the present invention the cavity housing the firstelectronic device is formed such that said first electronic deviceand/or said second electronic device is respectively are hermeticallysealed. In particular said first electronic device and/or said secondelectronic device is respectively are hermetically sealed in said cavityrespectively in between the contact side of the lid and the top side ofthe support substrate.

To provide the electrical contact to the housed first electronic deviceat least one first via-hole is fabricated into a bottom side of saidsupport substrate and/or a rear side of said lid allowing access to saidfirst electrical contact pad or connecting top said and bottom side ofsaid support substrate. Possible techniques for the fabrication of saidfirst via-hole are etching, lapping and/or sand blasting. If suitable,photo-lithographic techniques can be applied. The via hole or said firstvia-hole is fabricated as deep as allowing direct access to said firstelectrical contact pad. Accordingly, said first via-hole has a depthaccording to the thickness of said support substrate and a diameter inthe order of 1 .mu.m up to some hundreds .mu.m, preferably in the order50 .mu.m up to 200 .mu.m.

For establishing an electrical connection from said bottom side of saidsupport substrate or from said rear side of said lid trough said firstvia-hole to said first electrical contact pad and said first electronicdevice, an electrical connection, in particular at least one firstelectrical connection line, is fabricated. Possible techniques for thefabrication of said first electrical connection line are PVD, forinstance evaporation and/or sputtering, and/or CVD comprising thematerials Au, Al, Cu, AlSi and/or AlCu. If suitable, photo-lithographictechniques can be applied.

Enabling an easy further processing of the resulting electronic packagee.g. its mounting on a printed circuit board at least one first solderball is placed onto said first electrical connection line. A preferredtechnique for the mounting of said first solder ball is a reflowprocess, laser mounting, Au/Au floating process, conductive filminterconnecting process and/or Ag soldering. Accordingly, preferredprocesses involve a melting of prefabricated solder balls on said firstelectrical connection line. Said first solder ball has a diameter in theorder of 10 .mu.m up to some hundreds .mu.m, preferably in the order 100.mu.m up to 500 .mu.m comprising PbSn, SnAgCu and/or ZnSn.

According to the above mentioned particular preferred embodiment of thisinvention at least one second via-hole is fabricated into said bottomside of said support substrate or into said rear side of said lid,allowing access to said second electrical contact pad. Said secondelectrical via-hole can be fabricated by using the same technique andsame materials as mentioned above for said first via-hole. Preferablysaid first and said second via-hole are fabricated simultaneously in onestep. Said second via-hole allows access to said second electricalcontact pad.

According to this embodiment also an electrical connection, inparticular at least one second electrical connection line, is fabricatedtrough said second via-hole from said second electrical contact pad tosaid bottom side of said support substrate or to said rear side of saidlid. And also at least one second solder ball is placed onto said secondelectrical connection line. Said second electrical connection lineand/or said second solder ball can be fabricated by using the sametechnique and same materials as mentioned above for the correspondingsaid first electrical connection line respectively said first solderball, preferably they are mounted simultaneously.

Electrical connections or electrical connection lines between said firstcontact pads and said first electronic devices, between second contactpad and second electronic device and/or between first electronic device61 and second electronic device can be fabricated by using the sametechnique and same materials as for the above mentioned first electricalconnection line.

The above described photo-lithographic technique for depositionprocesses, as for instance PVD, comprises the steps of coating thesupport substrate with a photosensitive resist layer, photo-lithographicstructuring of the applied resist layer, coating the pre-structuredsubstrate with the corresponding layer which comprises the correspondingmaterial and lifting off the resist layer. The photo-lithographicstructuring step comprises mask exposure and subsequent developing. Thestep of coating can be carried out by spin coating, spraying,electrodeposition and/or by depositing of at least one photosensitiveresist foil. The step of lifting off the resist layer is carried out insuch a manner that at least one layer that has been applied to theresist layer is also lifted off. The fabrication of via holes orrecesses by photo-lithographic techniques is correspondingly applied.

Beside the mounting of the above mentioned components to form saidelectronic package, i.e. the mounting of the electronic package as asingle chip, the mounting can be performed in one preferred embodimentin a wafer assembly. Accordingly, a multitude of chips of the same typeare fabricated simultaneously. Said wafer assembly comprising saidmultitude of electronic packages is diced into single chips via sawing,lapping, sand blasting, laser cutting, diamond scribing and/or snapping.In a first embodiment each chip comprises said first electronic device,said cavity, said first electrical contact pad, said first via-hole,said first electrical connection line and said first solder ball. Saidelectronic package comprises a thickness in the order of 10 .mu.m up to5 mm, preferably in the order of 100 .mu.m up to 1 mm and a diameter inthe order of 1 .mu.m up to 200 .mu.m, preferably in the order of 10.mu.m up to 100 .mu.m. In another embodiment each chip comprises saidfirst electronic device, said cavity, said second electronic device,said first electrical contact pad, said second electrical contact pad,said first via-hole, said second via-hole, said first electricalconnection line, said second electrical connection line, said firstsolder ball and said second solder ball. Said electronic packagecomprises a thickness in the order of 50 .mu.m up to 2 mm, preferably inthe order of 100 .mu.m up to 1 mm and a diameter in the order of 500.mu.m up to 20 mm, preferably in the order of 1 mm up to 10 mm.

The method according to this invention enables an efficient fabricationof packaged electronic devices and of packaged electronic devices andtheir associated controller and/or driver integrated circuits.

The invention is explained subsequently in more detail on the basis ofpreferred embodiments and with reference to the appended figures. Thefeatures of the different embodiments are able to be combined with oneanother. Identical reference numerals in the figures denote identical orsimilar parts.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic side view of an electronic package comprising afirst electronic device being movable mounted and a second electronicdevice.

FIG. 2 shows a schematic side view of a further electronic packagecomprising a first electronic device and a second electronic device.

FIG. 3.a to 3.w schematically illustrate in a side view the processsteps to fabricate an electronic package according to the inventioninvolving a first electronic device.

FIG. 4 schematically shows an electronic package being producedaccording to the method illustrated in FIGS. 3.a to 3.w.

FIG. 5.a to 5.l schematically illustrate in a side view the processsteps to fabricate an electronic package according to the inventioninvolving a first electronic device.

FIG. 6 schematically shows an electronic package being producedaccording to the method illustrated in FIGS. 3.a to 3.w.

Subsequently, preferred but exemplar embodiments of the invention aredescribed in more detail with regard to the figures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The figures show the feature of a backside-contacting. The electroniccomponents, in particular the first and the second electronic device areelectrically contacted via the backside 1 b of said support substrate.

FIGS. 1 and 2 show a schematic side view of an electronic package 20comprising a first electronic device 61 and a second electronic device62 producible or produced with a method according to the invention. Theelectronic package 20 comprises a support substrate 1, which has atleast one recess 7 in its top side 1 a. Said support substrate 1 isbonded with a lid 4, which forms simultaneously a cavity 75 housing afirst electronic device 61 and an encapsulation of a second electronicdevice 62 placed adjacent to said recess 7 on said top side 1 a. Saidfirst electronic device 61 is connected to a first electrical contactpad 91. Said first electrical contact pad 91 is connected trough a firstvia-hole 101 and a therein placed first electrical connection line 31 toa bottom side 1 b of said support substrate 1 and is connectable by afirst solder ball 21, e.g. to a printed circuit board. Said secondelectronic device 62 is connected to a second electrical contact pad 92.Said second electrical contact pad 92 is connected trough a secondvia-hole 102 and a therein placed second electrical connection line 32to a bottom side 1 b of said support substrate 1 and is furtherconnectable by a second solder ball 22, e.g. to a printed circuit board.In FIG. 1 said first electronic device 61 is mounted on a stair 11. Inparticular said first electronic device 61 is movably mounted on saidstair 11. In FIG. 2, in contrast to FIG. 1, said first electronic device61 is directly mounted or placed onto the bottom 71 of the recess 7 andsaid first electronic device 61 can not be enabled to oscillate.

One fabrication method embodiment is subsequently explained in moredetail in FIGS. 3.a to 3.w. The illustrated method shows the packagingof electronic components on a wafer level. The method for packagingelectronic components according to FIGS. 3.a to 3.d comprises the firststep of providing a wafer or a support substrate 1. Said supportsubstrate 1 is a semiconductor substrate. Said support substrate 1comprises a thickness in the order of 50 .mu.m up to 500 .mu.m and adiameter in the order of 4″ up to 12″. FIG. 3.a shows a view onto thetop side 1 a of a support substrate 1. FIG. 3.b shows a zoom of thesection Z shown in FIG. 3.a. It is illustrated a partitioning of thewafer in sections 1 c. A fabrication or mounting of electroniccomponents or devices, for instance of the first and/or the secondelectronic device 61 respectively 62, occurs within these sections 1 c.FIG. 3.c and 3.d show a schematic side view or cross section of the zoomZ shown in FIG. 3.b along intersection line S. The shown supportsubstrate 1 has a top side 1 a and a bottom side 1 b.

FIG. 3.d to 3.i illustrate the fabrication of contact pads, for instanceof the first and second contact pads 91 respectively 92, by the usage ofphoto-lithographic techniques. It comprises the steps of coating thesubstrate 1 on its top side 1 a with a photosensitive resist layer 2(FIG. 3.e) and forming recesses 2 a are by a photo-lithographicstructuring of the applied layer 2 (FIG. 3.f). In a further step the topside 1 a of the substrate 1 is coated with a layer 9 of a conductivematerial, for instance a metal like Au, by a PVD process like electronbeam evaporation or sputtering. First electrical contact pads 91 areformed on the top side 1 a of the support substrate within said recesses2 a (FIG. 3.g). The resist layer 2 is lifted off in a further step (FIG.3.i) and the first electrical contacts pads 91 remain fixed on the topside 1 a (FIG. 3.i). The distance between said first electrical contactpads 91 is determined by the dimensions of said first electronic device61 to be mounted or by the section 1 c partitioning.

The method for packaging electronic components further comprises thestep of producing of at least one recess 7 in a top side 1 a of saidsupport substrate 1 by a subtractive process which is illustrated inFIGS. 3.j and 3.k. The dimensions of said recess 7 are adapted to thedimensions of said first electronic device 61 to accommodate. Thedimensions of said recess 7 are chosen such that said first electronicdevice 61 dives completely in said recess 7. The fabrication of saidrecess 7 is performed by ultrasonic-lapping. The dimensions of alap-tool or a lap-die is determined by the dimensions of the firstelectronic device 61 to accommodate within the produced recess 7. In oneembodiment of the invention said recess 7 comprises one stair 11 at abottom 71 of said recess 7. The dimensions of said stair 11 aredetermined by the dimensions of said first electronic device 61 tosupport and to space from said bottom 71 of said recess 7.

The fabrication of said stair 11 within said recess 7 or the fabricationof said recess 7 and said stair 11 is performed by lapping in a 2-stepprocess using two lap-dies, in particular a first lap-die 110 and asecond lap-die 111, having different dimensions according to thedimensions of said recess 7 and the dimensions of said stair 11 toproduce. In a first lapping process the first lap-die 110 is used tofabricate a first recess section 72 corresponding to the diameter of thetotal recess 7 reduced by the length of said stair 11. The lappingprocess is performed up to the desired depth of the recess 7 or recesssection 72. In a second lapping process a second lap-die 111 is used toincrease the recess 7 diameter by a second recess section 73 to thedesired recess diameter 7. Another option is based on a lapping in a1-step process using a lap-die with a shape corresponding to the desiredshape of said recess 7 and said stair 11 or the combined shape of saidfirst lap-die 110 and said second lap-die 111.

The method for packaging electronic components comprises as anadditional step the mounting or placing of one first electronic device61 into said recess 7 (FIG. 3.l). For instance said first electronicdevice 61 corresponds to an acceleration sensor. Accordingly, said firstelectronic device 61 is movably mounted on said stair 11 by gluing. Saidstair 11 supports and spaces said first electronic device 61 from thebottom 71 of the recess 7. Since said first electronic device 61 ismounted only at least on one of its sides, said stair 11 enables saidfirst electronic device 61 to oscillate to detect an affectingacceleration.

Said first electronic device 61 is electrically connected with saidfirst electrical contact pad 91 by wire bonding comprising the materialAu (FIG. 3.m). The inventive method further comprises the covering ofsaid top side 1 a of said support substrate 1 with a lid 4 (FIG. 3.n).Said support substrate 1 is covered by said lid 4 in an adjoiningrelationship by means of an adhesive layer 4, in particular a gluelayer, placed onto the bottom side 1 b of said support substrate 1.According to this embodiment, the covering by said lid 4 results in aformation of a cavity 75 housing said first electronic device 61. Apreferred cover comprises a glass plate having a thickness in the orderof 10 .mu.m up to some mm and a diameter corresponding essentially tothe diameter of said support substrate 1 to cover. Accordingly, said topside 1 a of said support substrate 1 and a contact side 4 a of saidcovering lid 4 are bonded together by gluing. A curing of the adhesivelayer 5 can be supported by irradiation. The adhesive layer 5 can bedeposited by spin coating and substantially can cover entirely saidcontact side 4 a of said lid 4. Said adhesive layer 5 comprises athickness in the order of 100 nm up to some tens .mu.m and a diametercorresponding essentially to the diameter of said lid 4.

The positioning of said first electronic device 61 within said cavity 75enables a simplified handling of the electronic package 61 in thefollowing process steps and an efficient protection of said firstelectronic device 61 e.g. against arising dust produced in the followingprocess steps.

The method for packaging electronic components comprises as a subsequentstep the providing of an electrical contact to the housed firstelectronic devices 61 (FIG. 3.q to 3.v). This is achieved by thefabrication of first via-holes 101 into a bottom side 1 b of saidsupport substrate 1 which allows an access to the first contact pads 91to contact the first electronic devices 61.

The shown via hole fabrication uses photo-lithographic techniques withthe steps of coating the substrate 1 on its bottom side 1 b with aphotosensitive resist layer 120 (FIG. 3.p). Recesses 120 a are formed bya photo-lithographic structuring of the applied resist layer 120 (FIG.3.q). In a further step the bottom side 1 b of the substrate 1 istreated in a selective etching process producing said via holes 101according to said recesses 120 a (FIG. 3.r). The corresponding via-holes91 are fabricated as deep as allowing direct access to said firstelectrical contact pads 91. The residual resist layer 120 is removed ina lift-off process (FIG. 3.s).

To establish the electrical connection from said bottom side 1 b of saidsupport substrate 1 to said first contact pads 91 the via holes 101 arefilled up with a conducting material 105 (FIG. 3.t). First electricalconnection lines 31 are fabricated by an evaporation process comprisingAu using photo-lithographic structuring as described above for thefabrication of the first contact pads 91 (FIG. 3.u).

To enable an easy further processing of the resulting electronicpackages 20, e.g. their mounting on a printed circuit board, firstsolder balls 21 are placed onto said first electrical connection lines31 (FIG. 3.u). A preferred technique for the fabrication of said firstsolder ball 21 is the reflow technique. The first contact pads 91 andthe first solder balls 21 are laterally shifted to each other. Avertical projection of the first contact pad 91 center and the firstsolder ball center 21 does not coincident. The vertical directioncorresponds to a direction perpendicular to the top side 1 a of thesupport substrate 1. FIG. 3.w shows the cutting or dicing of thefabricated wafer assembly. The assembly is cut along cutting lines C.Said cutting lines are positioned between said sections 1 c. A resultingelectronic package 20 is shown in FIG. 4. The electronic package 20comprises a thickness in the order of 50 .mu.m up to 2 mm and a diameterin the order of 500 .mu.m up to 20 mm. It can be mounted e.g. on anon-shown printed circuit board or on another non-shown circuitsubstrate that for instance provides power inputs and receivesinstrument outputs as required by the system in which it is to be used.Since the connecting lines 31 extend essentially parallel to the backside 1 b from the bottom side of the filling material 105 to a bottomside of a corresponding cavity 75 projection, a compact and space-savingdesign of the electronic package is enabled.

FIGS. 5.a to 5.l schematically show a further embodiment of the presentinventive method to illustrate the process steps involving the mountingof a first and a second electronic device 61 and 62. In case that thefabrication of a second component is not explicitly explained, thefabrication of a first component described in FIGS. 3 a to 3.w can beapplied also to said second component. For instance the deposition ofthe second electrical contact pads 92 is performed in the same manner orat least in a similar manner as the fabrication of the first electricalcontact pads 91.

FIG. 5.a shows the support substrate 1 after the fabrication of therecesses 7 and the deposition of the first and second electrical contactpads 91 and 92. First electronic devices 61, for instance opticaldetectors, are positioned onto the bottom 71 of said recesses 7 (FIG.5.b). Second electronic devices 62 are positioned, in particularadjacently to said recesses 7, on the top side 1 a of said supportsubstrate 1 (FIG. 5.c). In one embodiment of the present invention saidsecond electronic device 62 is an integrated circuit. In particular saidintegrated circuit is provided as a controller integrated circuit forsaid first electronic device 61.

The electrical connection of said first electronic device 61 and saidsecond electronic device 62 is illustrated in FIG. 5.d. The electricalconnection 81 of the first electronic device 61 with the firstelectrical contact pad 91 is performed by wire bonding. The connection82 between the second electronic device 62 and the second electricalcontact pad 92 is realized by metal pasting 82. The first electronicdevice 61 and the second electronic device 62 are electrically connectedvia the connecting line 83 which can be produced also by metal pasting.

One further step for packaging electronic components corresponds to acovering of said top side 1 a of said support substrate 1 with a lid 4(FIG. 5.e and FIG. 5.f). Said support substrate 1 is covered by said lid4 in an adjoining relationship via anodic bonding. A preferred cover orlid 4 is provided as a glass plate or a plate being at least transparentfor the radiation to be detected by said first electronic device 61.Accordingly, the covering by said lid 4 results in a simultaneousformation of a cavity 75 housing said first electronic device 61 and anencapsulation of said second electronic device 62. The position of saidfirst electronic device 61 within said cavity 75 and the encapsulationof said second electronic device 62 enable a simplified handling andenhanced protection of the electronic package 20 to be produced in thesubsequent fabrication steps.

FIGS. 5.g and 5.j illustrate the providing of an electrical connectionto the housed first electronic devices 61 and to the encapsulated secondelectronic device 62. The respective fabrication of the first and thesecond via holes 101 and 102 is illustrated in FIGS. 5.g to 5.i andcorresponds to the fabrication of the first via holes 101 as shown inFIGS. 3.q to 3.s. The first via-holes 101 and the second via holes 102allow access to the first respectively second electrical contact pads 91and 92.

To establish the electrical connection from said bottom side 1 b of saidsupport substrate 1 to said first respectively second contact pads 91and 92 the respective via holes 101 and 102 are provided or equippedwith first respectively second electrical connecting lines 31 and 32.Said first and second electrical connecting lines 31 and 32 can befabricated by photo-lithographic structuring according to the abovedescribed fabrication of the first contact pads 91. The respectivesolder ball deposition and wafer dicing (FIGS. 5.k and 5.l) correspondto the solder ball deposition and wafer dicing shown in FIGS. 3.v and3.w. The fabricated electronic package 20 after dicing is shown in FIG.6.

Since the first electronic device 61 and/or the second electronicdevices 62 are well protected by the housing within said cavityrespectively the encapsulation in between the contact side 4 a of thelid and the top side 1 a of the substrate, a disturbance or a damage ofthe electronic devices 61 and 62 can be reduced or even avoided.

A method of packaging electronic devices and of packaging electronicdevices with their associated integrated circuits has been shown. Itwill be understood that the invention may be embodied in other specificforms without departing from the spirit or central characteristicsthereof. The present examples and embodiments, in particular the abovementioned materials, therefore, are to be considered in all respects asillustrative and not restrictive, and the invention is not to be limitedto the details given herein. Above described sequence of method stepscan be exchanged in a reasonable manner.

REFERENCES

-   -   1 Support substrate    -   1 a Top side of the support substrate    -   1 b Bottom side of the support substrate    -   1 c Section of the top side 1 a    -   2 Resist layer    -   2 a Recess in the resist layer 2    -   4 Lid or cover    -   4 a Contact side of the lid 4    -   5 Adhesive layer    -   7 Recess    -   9 Conductive material layer    -   11 Stair    -   20 Electronic package or chip    -   21 First solder ball    -   22 Second solder ball    -   31 First electrical connection line    -   32 Second electrical connection line    -   61 First electronic device    -   62 Second electronic device    -   71 Bottom of the Recess    -   72 First section of recess 7    -   73 Second section of recess 7    -   75 Cavity    -   81 Connection between first contact pad 91 and first electronic        device 61    -   82 Connection between second contact pad 92 and second        electronic device 62    -   83 Connection between first electronic device 61 and second        electronic device 62    -   91 First electrical contact pad    -   92 Second electrical contact pad    -   101 First via-hole    -   102 Second via-hole    -   105 Conductive material filling    -   110 First lap-die    -   111 Second lap-die    -   120 Resist layer    -   120 a Recess in resist layer 120    -   200 Lift-off-direction    -   Z Zoom    -   S Intersection line    -   C Cutting line

1. A method for packaging electronic components comprising: a) providingat least one support substrate (1), b) producing at least one recess (7)in a top side (1 a) of said support substrate (1), c) placing at leastone first electronic device (61) into said recess (7), d) arranging atleast one second electronic device (62) on said top side (1 a) of saidsupport substrate (1), wherein said second electronic device does notoverlap the first electronic device (61), and e) covering at leastpartially said top side (1 a) of said support substrate (1) with a lid(4) to create a cavity (75), said first electronic device (1) is placedwithin said cavity (75), and wherein said lid (4) is in physicalcontacted with the top surface of said second electronic device.